Moldable article, method of making and composition for making moldable articles

ABSTRACT

A moldable article that can be custom-fitted to a particular user. Such an article comprises a thermoplastic material such as ethylene vinyl acetate modified by an antistatic agent selected from the group consisting of polyol amines such as ethoxylated amines, ethoxylated fatty alcohols, phosphoric acid esters, quaternary ammonium salts, and amphoteric compounds such as betaine. The article is heated until the thermoplastic material softens, then pressed against a user&#39;s body part. The article is allowed to cool, resulting in a custom-fitted article. Such articles may be repeatedly re-heated and re-molded and may include, e.g., moldable footbeds, racquet handles, shin guards, helmets, and seats.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to moldable articles andcompositions for making the same. In particular, the invention relatesto articles that are heat-moldable.

2. Background Art

It is becoming more and more desirable to provide wearers withcustomized articles for sporting goods and the like. Such articlesprovide the wearer with a greater degree of comfort and support. One waythis customization can be achieved is by producing articles thatsimulate the contours of a particular part of the body on which they areworn or used. Examples include footbeds that simulate the bottomcontours of the human foot, racquet handles that simulate the contoursof the hand, helmets that simulate the contours of the head, and shinpieces that simulate the contours of the lower leg.

A number of approaches have been developed to provide customizedarticles. In one approach, the article includes a layer of thermoplasticmaterial which will soften when heated. The wearer then presses a bodypart against the heated article, creating an impression. Thethermoplastic material is then allowed to cool while retaining theimpression of the wearer's body part. An example of this approach isdisclosed in U.S. Pat. No. 5,733,647. In this example, the thermoplasticmaterial comprises a mixture of ethylene copolymers and/or ethyleneterpolymers with an ethylene terpolymer such as ethylene vinyl acetatecoploymer modified by the addition of carbonyl groups incorporated aspart of the main chain. While the thermoplastic material disclosed inU.S. Pat. No. 5,733,647 can be heated and molded, it is a non-foammaterial which reduces the comfort provided by the article and microwaveheating a thermoplastic material that includes carbonyl groups in themain chain can result in the emission of toxic carbon monoxide fumes.Obviously, this is dangerous for consumers who may choose to mold thearticle at home.

Thus, the need exists for an article which can be custom molded in asimple and efficient manner, without the possibility of emitting toxicfumes.

BRIEF SUMMARY OF THE INVENTION

The present invention solves the above stated problems by providing anarticle that is efficiently heat-molded without releasing carbonmonoxide and which can be re-heated and re-molded. In particular, thearticle comprises a layer of modified ethylene vinyl acetate copolymer.Preferred modifying agents include polyol amines such as ethoxylatedamines, ethoxylated fatty alcohols, phosphoric acid esters, quaternaryammonium salts, and amphoteric compounds such as betaine. An articlemade from this composition can be heat-molded quickly and efficiently.The moldable article may be heated using microwave heating or otherknown heating methods. During heating, the article does not releasecarbon monoxide. Once heat-softened, an impression is formed in thearticle using, e.g., a body part, such as a head, foot, or lower leg.After the impression is created in the softened article such that itconforms to the contours of the body part, the article is allowed tocool, resulting in a custom-fitted article. If the user is unhappy withthe impression or uncomfortable with the fit, the process can berepeated by re-heating the article and re-creating the impression.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other features and advantages of the present inventionwill be apparent from the following, more particular description of apreferred embodiment of the invention, as illustrated in theaccompanying drawings.

FIG. 1 is a side view of a shoe incorporating a moldable footbed of thepresent invention with part of the toe portion of the shoe cut awayshowing part of the toe portion of the shoe in cross section.

FIG. 2 is a perspective view of the moldable footbed of FIG. 1.

FIG. 3 is a side view showing the process of molding the footbed of FIG.1.

FIG. 4 is a perspective view of a moldable racket handle being conformedto a user's hand.

FIG. 5 is a side view of a moldable shin piece being conformed to awearer's lower leg.

FIG. 6 is a side view of a moldable helmet being conformed to a wearer'shead.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the present invention is now described withreference to the figures where like reference numbers indicate identicalor functionally similar elements. Also in the figures, the left mostdigit of each reference number corresponds to the figure in which thereference number is first used. While specific configurations andarrangements are discussed, it should be understood that this is donefor illustrative purposes only. A person skilled in the relevant artwill recognize that other configurations and arrangements can be usedwithout departing from the spirit and scope of the invention. It will beapparent to a person skilled in the relevant art that this invention canalso be employed in a variety of other devices and applications.

FIG. 1 shows a side view of a shoe 100 having an upper 110, a flexiblesole 150, and a moldable footbed 140. As the term is used herein,footbed includes sockliners, insoles, and innersoles, as those terms aregenerally known to one skilled in the relevant art. Upper 110 may bemade of any conventional flexible material, such as leather, canvas,mesh, or other similar material, as would be apparent to one skilled inthe relevant art. Upper 110 has an ankle opening 112 designed to receivea foot.

Moldable footbed 140 is preferably made of a foam thermoplasticmaterial, preferably composed of modified ethylene vinyl acetatecopolymer (EVA) as described below. Moldable footbed 140 may beconnected to upper 110 and sole 150 by a fastening means, such as glue,cement, adhesive, stitching, or other means of attachment, as would beapparent to one skilled in the relevant art. However, moldable footbed140 need not be connected to the upper 110 or sole 150 at all. Instead,moldable footbed 140 may be inserted into ankle opening 112 and simplylay on top of a sole. In alternate embodiments, moldable footbed 140 mayonly cover the back portion of the foot, the front portion of the foot,or any selected areas of the foot, rather than the whole foot, as wouldbe apparent to one skilled in the relevant art.

Flexible sole 150 may be made of any conventional durable resilientmaterial such as rubber or other similar material as would be apparentto one skilled in the relevant art. Sole 150, as shown in FIG. 1, iscoupled to moldable footbed 140 and upper 110 by a fastening means, suchas glue, cement, adhesive, stitching, or any other means of attachmentas would be apparent to one skilled in the relevant art.

In an alternate embodiment, a cushioning layer 242 may be provided aboveor below moldable footbed 140, or both, but preferably, such cushioninglayer 242 would be provided below moldable footbed 140 as part of sole150, as shown in FIG. 2. Cushioning layer 242 may be a flexible foamsuch as polyethylene foam, and may be used to provide additionalinsulation and cushioning. For example, moldable footbed 140 may berelatively thin to provide the wearer with the customized fit.Cushioning layer 242 provided below moldable footbed 140 may be aconventional midsole type material to provide additional cushioning, andmay be laminated.

In a preferred embodiment, moldable footbed 140 is made of athermoplastic material, comprised of a modified polymer. Preferably,moldable footbed 140 is approximately flat, to allow consistent,predictable, and even heating. Moldable footbed 140 may be any thicknesssuitable for use in footwear, preferably between 1 millimeter and 5centimeters, and more preferably between 3 and 8 millimeters.

In a preferred embodiment, the polymer comprises ethylene vinyl acetatecopolymer (EVA) or rubberized EVA modified with an antistatic(electrostatic dissipating) agent, preferably a polyol amine, such asethoxylated amines, and preferably NOROPLAST 2000 series, NOROPLAST 8000series, or NOROPLAST 832 available from Elf-Atochem of France.Ethoxylated fatty alcohols, phosphoric acid esters, quaternary ammoniumsalts, and amphoteric compounds such as betaine may also be used. Othermaterials may also be used, such as ZELEC® ECP made by E.I. duPont deNemours and Company of Wilmington Del. Different ZELEC® DCP productsconsist of an antimony-doped tin oxide outer shell with either a hollowsilica core, a mica core, a titanium dioxide core, or no core particle.Another DUPONT product which may be used in combination with EVA isAVITEX®, which is a sodium salt of sulfated oleyl actates. Other similarmaterials utilizing the desirable properties of the above materials mayalso be used with the polymer, as would be apparent to one of ordinaryskill in the relevant art.

In a preferred embodiment, the modifying agent is an amine derivative ofthe formula R¹N(R²)₂, wherein R¹ is a hydrophobic alkyl group and R² isan alkyl group substituted by at least one of OH, CO₂H, or CO₂R³, whereR³ is an alkyl; and the like. Preferred groups of R² includehydroxyalkyl groups. Most preferably, R² is hydroxyethyl. As usedherein, the term “hydrophobic alkyl group” refers to a naturallyoccurring lipid per se, a hydrophobic branched or unbranched hydrocarboncomprising approximately 4 to approximately 26 carbon atoms, preferablyapproximately 5 to approximately 19 carbon atoms, or a fatty acid orester thereof. Suitable hydrophobic alkyl groups include, but are notlimited to, long chain alkonoyl groups such as palmityl (C₁₅H₃₁), oleyl(C₁₅H₂₉), steoryl (C₁₇H₃₅), lauryl (C₁₁H₂₃), cholyl, and myristyl(C₁₃H₂₇).

In a most preferred embodiment, the modifying agent is NOROPLAST 2002, apolyol amine derivative available from Elf-Atochem. It has a reportedtotal alkalinity of between 3.25-3.60 ml HCL(n)/g. The total alkalinity(1+2) is preferably 2% by weight or lower. At 25° Celsius, it is ahomogeneous liquid with a specific gravity between 0.890-0.925, and aviscosity of approximately 122 mPa. Preferably, it has a pour point of8° C. or less, is 0.5% by weight or less water, and has no flashpoint upto 100° C.

Preferably, the thermoplastic material of moldable footbed 140 iscomprised of approximately 30% by weight or less modifying agent inliquid phase. In a more preferred embodiment, the thermoplastic materialof moldable footbed 140 is comprised of between approximately 10% byweight and approximately 30% by weight modifying agent in liquid phase.In a most preferred embodiment, the thermoplastic material of moldablefootbed 140 is comprised of approximately 70% by weight EVA andapproximately 30% by weight modifying agent in liquid phase. It ispreferable to minimize the mass of the non-thermoplastic material inmoldable footbed 140 so that the thermoplastic material may be heatedmore quickly. Longer heat times are undesirable because they may lead tothe emission of toxic fumes. In an alternate embodiment, thethermoplastic material of moldable footbed 140 may also comprise acement, such as n-heptane, acetone, or cyclohexanone, as would beapparent to one skilled in the relevant art.

The thermoplastic material of moldable footbed 140 may be formed by thefollowing steps:

1. Mixing the EVA with the modifying agent;

2. Rolling the mixture;

3. Sheet processing the mixture;

4. Heating the mixture;

5. Cooling the mixture; and

6. Splitting the mixture.

In the embodiment shown in FIG. 2, moldable footbed 140 may be removablefrom shoe 100. In this way, moldable footbed 140 may be custom-fitted tothe foot of a wearer by heating it to a preselected softening point, tosoften the thermoplastic material. In one embodiment, moldable footbed140 is heated by placing it in a conventional microwave oven untilmoldable footbed 140 is soft and compliant. Preferably, a pair ofmoldable footbeds 140 are heated in a conventional microwave oven(700-1000 watts). In a preferred embodiment, moldable footbeds 140 areheated in a 1000 watt microwave oven on high power for approximatelythree minutes. It is known that there are significant variations in theheating abilities of microwave ovens. Thus, various other size microwaveovens, heating times and heating methods could be used, as would beapparent to one skilled in the relevant art. In a less preferredembodiment, moldable footbed 140 may be heated by placing it in aconventional oven for a suitable time to soften the thermoplasticmaterial. Alternatively, moldable footbed 140 may be heated using anyheating means, for example, by placing it in a water-tight container inboiling water for a suitable time.

After moldable footbed 140 is softened through a heating process, theuser may then mold footbed 140 to the contours of the wearer's foot tocreate a custom fit. In a preferred embodiment, as shown in FIG. 3, awearer may place moldable footbed 140 on a cushion 362, such as aconventional bed pillow, stack of towels, or other suitable object, andpress foot F against moldable footbed 140, allowing moldable footbed 140to form to the contours of foot F. Foot F may continue to press againstmoldable footbed 140 until moldable footbed 140 substantially cools,resulting in a custom-fitted article. If the fit is not correct,moldable footbed 140 may be reheated, resoftened, and remolded to reformmoldable footbed 140 to the contours of foot F.

In a preferred embodiment, both moldable footbeds 140 of a pair of shoesmay be heated together in a microwave oven. Preferably moldable footbeds140 may be heated on a non-energy absorbing, rotating microwave tray.Using a microwave oven without a rotating microwave tray may lead touneven heating. A preferable rotating microwave tray is one that absorbsenergy and uses the conduction of heat to soften footbed 140, such asone made of glass. In an alternate embodiment, a polypropylene microwavetray could be used. Non-energy absorbing rotating trays leave moreenergy available to heat footbed 140. In an alternate embodiment, amicrowave tray may be used that includes an outline of one or twoinsoles. Such an embodiment would facilitate consistent placement ofmoldable footbeds 140, which is important for consistent, predictable,and even heating. Moldable footbeds 140 may also be turned or invertedduring the heating process. Preferably, footbeds 140 are heated rightside up without being inverted or turned during the heating process.Alternatively, footbeds 140 may be heated upside down so that the topportion of moldable footbeds 140 are softened more than the bottomportion of footbeds 140. This allows the top portion of moldablefootbeds 140 to easily form to the contour of a wearer's foot, whileallowing the bottom portion of footbeds 140 to remain stiffer, thusreducing the chance of folding or buckling when being placed in theshoe.

The thermoplastic material of the present invention may be used to makemoldable articles other than footbeds. As shown in FIG. 4 a moldablehandle 472 of a racquet 470 may be composed of the same thermoplasticmaterial described above. Racquet handle 472 may heated and softened insubstantially the same way as described above. A wearer may then placehis hand H around racquet handle 472, forming an impression. The wearermay keep hand H around racquet handle 472 until it cools, resulting in acustom-fitted racquet handle. In alternate embodiments, a moldablehandle of the present invention could be used as a luggage handle, orany other type of handle, as would be apparent to one skilled in therelevant art.

The heat-moldable thermoplastic layer according to the present inventionmay also be useful in a shin guard 580, as shown in FIG. 5. Thethermoplastic layer may be in the form of a removable insert for aconventional shin guard that may be heated and softened in substantiallythe same manner as described above. The insert may then be pressedagainst a wearer's shin S and allowed to cool, resulting in acustom-fitted shin guard.

Other articles, such as a helmet 690, as shown in FIG. 6, may becustom-fitted to a wearer using the present invention. Helmet 690 mayinclude a removable thermoplastic layer according to the presentinvention. The insert may be heat-softened and pressed against awearer's head H. When the insert cools, the wearer is provided with acustom-fitted helmet 690.

A heat-moldable article of the present invention could also be used as aseat for a wheelchair, a child's car seat, or any other type of seat, aswould be apparent to one skilled in the relevant art.

While the present invention has been particularly shown and describedwith reference to molding using body parts, which are preferredembodiments thereof, it will be understood by those skilled in the artthat molding using other articles and other various changes in form anddetails may be made thereto, without departing from the spirit and scopeof the invention.

What is claimed is:
 1. A footbed comprising a moldable layer consistingessentially of ethylene vinyl acetate copolymer and an antistatic agent.2. The footbed of claim 1, further comprising: a cushioning layer belowsaid moldable layer.
 3. The footbed of claim 1, wherein said antistaticagent is selected from the group consisting of a polyol amine, anethoxylated fatty alcohol, a phosphoric acid ester, a quaternaryammonium salt, and an amphoteric compound.
 4. The footbed of claim 3,wherein said antistatic agent is a polyol amine.
 5. The footbed of claim4, wherein said polyol amine is an ethoxylated amine.
 6. The footbed ofclaim 1, wherein said antistatic agent is an amine derivative having theformula R¹N(R²)₂, wherein R¹ is a hydrophobic alkyl group and R² is analkyl group substituted by at least one of OH, CO₂H, or CO₂R³, whereinR³ is an alkyl.
 7. The footbed of claim 6, wherein R² is a hydroxyalkylgroup.
 8. The footbed of claim 6, wherein R² is hydroxyethyl.
 9. Anarticle having a moldable layer consisting essentially of, ethylenevinyl acetate copolymer and an antistatic agent, wherein said layercomprises approximately seventy percent by weight ethylene vinyl acetatecopolymer and approximately thirty percent by weight antistatic agent.10. An article consisting essentially of, ethylene vinyl acetatecopolymer and an antistatic agent, wherein said article is a footbed andused to cushion a part of the body.